1. Field of the Invention
The present invention relates to an electronic device with an opening/closing door such as an LCD projector including a shutter system.
2. Description of Related Art
In an LCD projector for projecting images onto a screen, there has been a need for temporarily suspending image projection onto the screen while causing a light source for the image projection to stay on. By way of example, in a conventionally used LCD projector, a shutter system constituted by a plurality of shutters is arranged between an optical device with a color synthesizing prism and the like and a light source. The shutter system is closed by rotating the plurality of shutters, thereby temporarily interrupting the passage of light.
The conventionally used LCD projector requires the complicated structure of the shutter system due to the need for rotating the plurality of shutters. In response, a shutter system 100 shown in FIG. 12 has been proposed. The shutter system 100 includes a pair of doors 101 and 102 for interrupting light that respectively move up and down. More specifically, in addition to the pair of doors 101 and 102, the shutter system 100 includes a motor 103, an arm 104, a gear 105 for transmitting the rotation of the motor 103 to the arm 104, and a mounting table 106 for holding these parts thereon. An opening 107 through which light passes is defined in the mounting table 106.
The doors 101 and 102 in a pair are arranged above and below the opening 107 respectively, and can slide along a surface of the mounting table 106. More specifically, the doors 101 and 102 in a pair are fixed to sliding plates 108 and 109 respectively that are slidably arranged on opposite sides of the opening 107. When the sliding plates 108 and 109 slide up and down, the doors 101 and 102 in a pair also move (slide) up and down.
The arm 104 is rotatably supported on the mounting table 106. More specifically, the arm 104 is supported at a central part 110 on the mounting table 106. Further, the arm 104 is so arranged that a pivot point 111 of the arm 104 is placed on a center line 119 of the width of the doors 101 and 102. Thus, opposite ends 112 and 113 of the arm 104 are allowed to move about the pivot point 111. More specifically, while the end 112 (113) moves up about the pivot point 111, the end 113 (112) moves down about the pivot point 111. The arm 104 is caused to pivot by transmitting the rotation of the motor 103 through the gear 105 to the arm 104.
The opposite ends 112 and 113 of the arm 104 respectively engage with the sliding plates 108 and 109 in a pair. By fitting projections 121 and 122 provided to the shutter system 100 into holes 123 and 124 defined in the sliding plates 108 and 109 respectively, the sliding plates 108 and 109 are guided so as to move straight up and down. So, the pivotal movement of the arm 104 about the pivot point 111 causes the sliding plate 108 engaging with the end 112 of the arm 104 to slide down, while causing the sliding plate 109 engaging with the end 113 of the arm 104 to slide up. Thus, the door 101 moves down while the door 102 moves up. As a result, the opening 107 is covered with the pair of doors 101 and 102, thereby interrupting light from the light source.
When the arm 104 is caused by the motor 103 to pivot about the pivot point 111 in the opposite direction, the sliding plate 108 engaging with the end 112 of the arm 104 slides up, and the sliding plate 109 engaging with the end 113 of the arm 104 slides down as shown in FIG. 12. Thus, the door 101 moves up while the door 102 moves down. As a result, the opening 107 is exposed so that light from the light source is allowed to pass through the opening 107.
The shutter system 100 including only the pair of doors 101 and 102 has a complicated structure, and a high degree of accuracy is required to smoothly open and close the doors 101 and 102, resulting in high cost of manufacturing the shutter system 100. Further, the pair of doors 101 and 102, and the arm 104 are held on the same surface of the mounting table 106 in the shutter system 100. So, the pair of doors 101 and 102, and the arm 104 should be arranged in a manner that avoids the interference therebetween, resulting in the upsizing of the shutter system 100.
Further, the pair of doors 101 and 102, and the arm 104 held on the mounting table 106 in the shutter system 100 are covered with a cover member 115. So, it is difficult to open and close the doors 101 and 102 by hand when the motor 103 breaks down.